1. Field of the Invention
This invention relates generally to a housing structure including a keyboard pad assembly for containing and operating an electronic device contained therein. More particularly, this invention relates to a housing structure including a keyboard pad assembly which is specifically designed and manufactured to protect the electronic device for operating in adverse environmental conditions, e.g., the dusty, moist and muddy conditions.
2. Description of the Prior Art
The performance of an electronic device is often very sensitive to environmental conditions in which the device is operated. Continuous and reliable outdoor operation of an electronic device is particularly limited by the concerns that the device may be subject to moist, muddy, dusty, and other types of potentially hazardous environmental conditions. This concern often limits the usefulness of certain types of electronic devices such as a portable global position system (GPS) receiver since it needs to receive signals from satellites while outdoors such that the satellites signals are not blocked by any type of obstructions. GPS receivers are often used by sailors while at sea, or by outdoorsman and soldiers in rural areas, and therefore may often be subject to adverse environmental conditions. Besides GPS receivers, with the widespread use of electronic use of electronic devices in society's daily activities, the demand for apparatuses and methods to overcome difficulties posed by operation in adverse environmental conditions are becoming more important.
Electronic apparatuses are becoming conveniently portable because of miniaturization of integrated circuits (ICs). As inexpensive microprocessors capable of handling highly complicated processes at very high speed are widely available, portable electronic apparatuses are being provided with user interfaces including keyboards, mouses, joysticks, optical scanners, notepads, voice synthesizers, etc. It is anticipated that the use of such portable electronic apparatuses will include many kinds of working environments such as in factories, grocery stores, warehouses, football fields, ships, airplanes, wilderness, and many other places under various environmental situations and conditions. For these types of applications, the user interfaces must be easily accessible, conveniently operable, and properly insulated from the potential environmental hazards so that their performance is not adversely affected.
A variety of small electrical switches are commonly used to operate apparatuses, but environmental inclosure, labeling, and actuation of the switches are normally accomplished by a keypad of some sort. Generally keypads are either separate, rigid parts or flexible membranes.
For outdoor operation, the portable GPS receivers currently available on the market require that users carefully handle the receivers to avoid potentially hazardous environmental conditions. Generally the most vulnerable part of the receivers is the user interface keys which provide mechanical contacts with electrical switches to operate the receivers. These keys must be exposed to provide easy close to the electrical switches to provide for the mechanical contact. The electric switches are therefore subject to exposure to various adverse operation conditions. With conventional keyboard structures, a malfunction of these switches or other parts of the GPS receivers is likely to occur once the GPS receivers are placed in a moist, dusty or muddy outdoor environment which may adversely effect the connection of the switches or the performance of other parts of the electronic circuits.